LSX_Corolla

I aquired a 98 Camaro that had been swapped to an LQ4 about a year ago. I bought it with no intake , TB, injectors or rails - the guy was going through a divoce or something. The motor was a plus as I was just searching for a T56 at the time. I through a factory intake setup on it and plugged it all up but when it had the IAT plugged up it ran like crap...Soo, I just left it unplugged, test drove the car a bit, and took it apart.

Fast forward to now. I have swapped the engine and trans into my car and everything is a go, except, when I have that sensor plugged in it goes haywire - it idles fine but whatever percent of throttle you give it wants to bog an die, but when let off it will rev up to what you thought it should have...if you progressively do that it maxes out at about 2500 RPM. If you have the sensor unplugged, the car runs great and throttle response is instant and it idles about 100-200 RPMs higher.

Any ideas on what this might be? something in a tune? It was tuned by Frost is what the previous owner told me.

-Nick

brandon6.0

iTrader: (32)

what intake setup did he previously have on it? Iat shouldn't cause any problems like that I would think. Unless its a bad sensor. have u swapped sensors?

The Iat changes up timing in the tune. Stock iat table has pretty safe timing. Its pulls around 3-4* timing around 90-100* ambient temp.

Weird situation u have there. U will probably need a new tune.

LSX_Corolla

I have used about 3 sensors, all with same results.

He had an LSX intake, NW 102, and "green top Bosch" injectors. I just installed all stock LS1 on my build.

yes, I agree it's strange. It almost seems to go into some limp mode..

T/A KID

iTrader: (12)

If it's tuned in SD then half the fuel calc is done with the Iat

LSX_Corolla

how can I tell if its a SD tune? I have HPT and the tune and can look at any aspect of it.

brandon6.0

iTrader: (32)

Yea like TA kid says it was probably a SD tuned car. And with those mods he had done it will need a retune for sure. He has different injector data as well. New tune needed. Or flash back to an original stock file to start over from.

brandon6.0

iTrader: (32)

If he has the maf sensor failed a 0HZ its a SD tune. Maf codes p101-103 will most likely have the ses box unchecked. And High octane table will match the low table. When in SD mode the PCM converts to the lower timing table. Dynamic air will be disabled. all of these will be a true SD tune.

brandon6.0

iTrader: (32)

Post up the tune.

LSX_Corolla

I have attached the tune file that I took off the car - I should mention the guy I had got it from also has a 228 236 112 cam in it as well...other than than, stock engine w LS1 items.

JoeNova

You can open the tune in the editor and click the OS tab, it should tell you if its been converted to an SD or if he's still playing around with a MAF tune.

LSX_Corolla

yes, in the OS it does have a box for SD 2 I believe. so id SD takes out the MAF, should I be able to remove the MAF for now and have my local tuner tune for SD with the parts that are n the car, or should I have him convert it back to MAF tune...

JoeNova

If its setup for SD, its not using the MAF for anything.
With HPT hooked up, screenshot the log to show what happens when you plug in the IAT. Is it pulling timing, adding fuel, throwing codes?

JoeNova

If he had boost or nitrous at any point, the IAT sensor is often used for timing control.
The log should show IAT temps before you plug it in, and after you plug it in as well as timing changes.

LSX_Corolla

Here are some screen shots of a log - first with no IAT, then at a point where i was giving throttle and it was wanting to die with enough around to see it idle with it plugged in..

and I'm fairly sure he had no boost or nitrous on the car.

brandon6.0

iTrader: (32)

Its pulling a lot of timing. Shows 3.2 degrees with it plugged in. Without your showing 22*. ALso without it, it is basicly in limp mode with a -38* temp. PCM reads only to -40*

brandon6.0

iTrader: (32)

looks to me u are still using the maf. The 2 bar modification hasn't been added yet.

Looking at the tune. With the iat unplugged u are commanding openloop until 140* coolant temp, with that u are adding a lot of fuel which this setup may need. Hinse it running better. Also under the idle spark underspeed has been zero out. Try changing that back stock and multiply by .50 or half the values from stock. do this and see if your idle spark does better with iat plugged in.

Also u can use the scanner to control idle spark timing. Try using that and see what happins.

LSX_Corolla

When it isnt plugged in it runs like a champ, throttle responsive etc, normal idle plugged in is ab 17-18* timing, give it gas it drops to ~3.

brandon6.0

iTrader: (32)

get a full scan and post up of both.

LSX_Corolla

When you say a full scan, what do you want to see? Just a moving scan, or particular aspects/measurements?

JoeNova

Any chance your IAT and MAP sensor wires are crossed?

I noticed in the screenshot with the IAT plugged in you were at 100 KPA with 63% throttle.